The iSCSI client or host (also known as the iSCSI initiator) is a system, such as a server, which attaches to an IP network and initiates requests and receives responses from an iSCSI target. Each iSCSI host is identified by a unique iSCSI Qualified Name (IQN), analogous to a Fibre Channel worldwide name (WWN).
The Microsoft iSCSI Initiator service supports the usage and configuration of Challenge Handshake Authentication Protocol (CHAP) and Internet Protocol security (IPsec) for both the Microsoft iSCSI software initiator and iSCSI host bus adapters (HBAs). All supported iSCSI HBAs support CHAP, while some may or may not support IPsec.
If you are using RADIUS, setting the iSCSI Initiator’s CHAP secret is not necessary when using mutual CHAP.
The CHAP secret must be 12-16 characters in length unless you are using IPsec, in which case, it can be as short as 8 characters.